Sail boat engine choice - electric or diesel

[waterman46]

Originally Posted by wingssail

And MOST OF ALL, regardless of how nice and quiet and clean and simple an electric purports to be, the fact that you cannot carry a fuel source to go 500 miles means they are a non-starter for the vast majority of cruising vessels. When they can, come back to us.

Yes, but those 500 miles must be while bashing to weather in 20 knots of wind with 6' wind waves and making at least 4 knots. And doing so day after day during a week of no sun and no connection to shore power.



The bottom line is that electric may be suited for specialty boats in short range applications, but for the vast majority of actual cruisers it just is not practical. Saying you need to put a 6' propeller on a cruising boat just loses any sense of reality and is simply laughable.

I'm not interested in filling the boat with batteries. I'm not interested in dragging down my sailing speed by several knots using a repeller to re-charge batteries.

If we discuss using normal propellers and large electric motors with a modest battery bank backed up with a diesel generator, then I am mildly interested, but how could that be more efficient than direct shaft drive from the same HP diesel?

[carstendenmark]

Thank you, all !

After all your kind inputs, I now simply want to get rid of my 44 yo. too-small-powered diesel and fit a bigger HP electric motor (), that can be run with a genset for long passages.
And fit the largest possible feathering 2-3-4 blade prop on my saildrive (or on a new shaft drive), geared by a toothbelt drive.
All with the present available technology.
The 29' boat is for cruising in Denmark and the Baltic.
Cost is not an issue.

[s/v Jedi]

My hat off to all who took the step to electric for their auxiliary engine. All who advocate diesel powered engines will look lost when there’s no diesel to be had and whine about how no one could have seen that coming.

Sailors use their sails. If their propulsion battery is low and they need the auxiliary engine to get out of the bay, they wait until the sun charged that battery, just like how our ancestors had to wait for the right wind and used row boats to manoeuvre out of the bay. We can still use side-tied dinghies with outboard motors.

Those who joke about boats with solar having “heli platforms” and how ugly that is are utterly clueless on why people do that and what sailboat cruising and life is about. Note that they normally write such posts from marina slips with big shore power cords.

We were one of the early ones with a substantial solar array on a monohull. Because of the size of our boat, we were able to mostly “hide” the 6x 110W panels. Now (16 years later) that those are worn out and we upgraded to an all electric galley, we’re upgrading to triple that capacity and get our heli platform too (it will conveniently shade our dinghy when hoisted for the win).

We still have our 140hp Yanmar which still runs great but I’m checking out all the electric options every couple of months to keep an eye on developments and hope to find an option that fits us when the time comes to replace the engine

[Chotu]

Originally Posted by s/v Jedi

My hat off to all who took the step to electric for their auxiliary engine. All who advocate diesel powered engines will look lost when there’s no diesel to be had and whine about how no one could have seen that coming.

Sailors use their sails. If their propulsion battery is low and they need the auxiliary engine to get out of the bay, they wait until the sun charged that battery, just like how our ancestors had to wait for the right wind and used row boats to manoeuvre out of the bay. We can still use side-tied dinghies with outboard motors.

Those who joke about boats with solar having “heli platforms” and how ugly that is are utterly clueless on why people do that and what sailboat cruising and life is about. Note that they normally write such posts from marina slips with big shore power cords.

We were one of the early ones with a substantial solar array on a monohull. Because of the size of our boat, we were able to mostly “hide” the 6x 110W panels. Now (16 years later) that those are worn out and we upgraded to an all electric galley, we’re upgrading to triple that capacity and get our heli platform too (it will conveniently shade our dinghy when hoisted for the win).

We still have our 140hp Yanmar which still runs great but I’m checking out all the electric options every couple of months to keep an eye on developments and hope to find an option that fits us when the time comes to replace the engine

Right on!

This is exactly why, other than weight, I chose outboard power for my boat.

They are modular. When the next breakthrough in technology occurs, it’s an easy upgrade. Be it to electric or to fusion reactors, or matter/antimatter reactors.

My boat is ready!

[seandepagnier]

Originally Posted by newhaul

I really think you need to actually answer my questions concerning your battery bank .
Read a couple pages back you will find them . I am a retired Navy engineer . I'm the guy that had to make the idiot ideas coming out of Norfolk work.
Sorry but your ideas while intreguing are lacking some serious technical backup.
In other words I doubt your word as to the numbers .

I found these cells on ebay for $1.50 each (free shipping) They are 18650 cells and I have 36 of them. Each cell is 2200mah capacity with average voltage 3.7.


I have arranged in 12 cells 3 parallel, so the nominal voltage is 44.4 volts and capacity 6.7 amp hours.



Capacity: 300 watt hours.

Weight is 68 ounces (with bms) or 4.25 pounds or 1.93kg.

Cost $54 for the battery and $11 for the bms (45 amp for efficiency), total: $65


You can build batteries of much larger capacity using this method just multiply the cost weight and capacity to find the result.

[seandepagnier]

Originally Posted by wingssail

seandepagnier, I think it was me that proposed 500 miles as a meaningful target for motoring capability, not newhaul or skipmac, so I am the one you should dismiss as unimaginative and a bad engineer, not them.

The bad engineer is from not knowing (or bothering to google) what an electric motor constant is, but instead making lengthy arguments regarding electric motors and horsepower using only knowledge of diesel powered inboards to come up with the resulting figures.

It was stated that if the boat cannot motor 500 miles it makes electric a non-starter for the majority of cruisers. This statement is what I call nonsense.

It seems with a $7000 battery I could actually motor 500 miles at 2 knots but I have no desire to ever do this. I could also motor at 2 knots in overcast conditions using my solar array, and 3-4 knots (to be demonstrated) when the sun is out. Electric range will always exceed fuel range when solar panels harvest energy underway.


Motoring for long distances seems only to compensate for unwillingness to harness the power of the wind. You cannot motor 500 miles (or even 100 miles) without any wind or sun available the whole way. It is unrealistic and essentially invalidates this "requirement"


Regardless, there will be a day soon when it simply won't be legal for anyone to use diesel power for non-essential activities. It's best to get the act together now and figure out the best way to deal with this, because when cars are forced to be electric, no one is going to care about your leisure activies. My own cruising experience would have been improved if no one else used diesel power (they spoil it polluting the air and water in harbors without even bothering to use catalytic converters) The fumes from diesel spills give me headaches and the harbor here has a slick more often than not. My best experiences are meeting other engine-free cruisers.

[newhaul]

Originally Posted by seandepagnier

I found these cells on ebay for $1.50 each (free shipping) They are 18650 cells and I have 36 of them. Each cell is 2200mah capacity with average voltage 3.7.


I have arranged in 12 cells 3 parallel, so the nominal voltage is 44.4 volts and capacity 6.7 amp hours.



Capacity: 300 watt hours.

Weight is 68 ounces (with bms) or 4.25 pounds or 1.93kg.

Cost $54 for the battery and $11 for the bms (45 amp for efficiency), total: $65


You can build batteries of much larger capacity using this method just multiply the cost weight and capacity to find the result.

I wold never myself consider a setup like that on a boat to many connections and to many points for failure not to mention it takes up many times more space than its ah value.
But I still doubt your speed and distance with only 6ah .

[seandepagnier]

Originally Posted by newhaul

And yes it can run on biodiesel but why pay double .

not sure about biodiesel but coconut oil fumes are far less hazardous to your own health, smell nice and are better for the engine. The cost of fuel should be negligible compared to for example buying food.

[newhaul]

Originally Posted by seandepagnier

Regardless, there will be a day soon when it simply won't be legal for anyone to use diesel power for non-essential activities. It's best to get the act together now and figure out the best way to deal with this, because when cars are forced to be electric, no one is going to care about your leisure activies. My own cruising experience would have been improved if no one else used diesel power (they spoil it polluting the air and water in harbors without even bothering to use catalytic converters) The fumes from diesel spills give me headaches and the harbor here has a slick more often than not. My best experiences are meeting other engine-free cruisers.

Sorry to tell you this but the day when Dyno juice is not allowed will never happen at least not in my ( or even my grandchildrens ) lifetime.

You really don't think that electric motivation is any more ecologically friendly that Petro . You really need to do a lot more research.

That being said I'm glad it works for you . Just stay out of shipping lanes at night .

[newhaul]

Originally Posted by seandepagnier

not sure about biodiesel but coconut oil fumes are far less hazardous to your own health, smell nice and are better for the engine. The cost of fuel should be negligible compared to for example buying food.

Ever hear of fishing ?

Two main problems with biodiesel is you end up smelling like a rancid MacDonald's
And the other is the cost difference between it and petroleum diesel.
Next is ( at least here ) coconut oil is exorbitantly priced to use as fuel for an engine.
$6 USD per gallon. And will ruin my diesel furnace.

[wingssail]

Originally Posted by waterman46

Yes, but those 500 miles must be while bashing to weather in 20 knots of wind with 6' wind waves and making at least 4 knots. And doing so day after day during a week of no sun and no connection to shore power.

Actually Waterman46, That is not when you need that motoring range. In those conditions you can be sailing, though not pleasantly for most boats. When you need that kind of powering range and why I find it to be a requirement, is when you are making a passage and there is no wind. I was happy to have that kind of capability when crossing the Pacific although we didn't need to use it. Another boat, a steel boat with the delightful name of "Rumple Steel Skin" couldn't sail well in light air and coming from the Galapagos used all their fuel (and water, and food; bad planning)

Closer to home I might want to go to La Paz from Puerto Vallarta. There have been times when the forecast was for wind but in fact the Sea of Cortez was calm for several days. Once you get out of Banderas Bay and you get a few miles you run out of wind and then you sit. Maybe for a day, maybe for a week. That 350mile trip can be powered with 500 miles of range.

There are people who will propose that one should just wait for the wind. OK, I accept that. And for them that kind of motoring range is not a requirement

Originally Posted by s/v Jedi

...Those who joke about boats with solar having “heli platforms” and how ugly that is are utterly clueless on why people do that and what sailboat cruising and life is about. Note that they normally write such posts from marina slips with big shore power cords...

Jedi, I don't know who coined that phrase, but I have used it. It's not a joke, and I'm not clueless as to why people do that to their boats (install massive arrays of solar over the transom). I just think it is not pretty and it is harmful in multiple ways to the sailing ability of the boat (of course it improves the electrical power generating ability of the boat). There is the trade off and it is one I would not make.

I think that people who value the sailing performance of their boats, and value the beauty of them, can still know what sailboat cruising and life are all about. For those who feel that a large platform filled with solar panels hanging over the backs of their boats is beautiful, and has no effect on the sailing performance; they have a different aesthetic than I do, which is fine, I'm used to being an outlier.

[MichaelPrichard]

Originally Posted by newhaul

I wold never myself consider a setup like that on a boat to many connections and to many points for failure not to mention it takes up many times more space than its ah value.
But I still doubt your speed and distance with only 6ah .

This always confuses me; a common complaint about electric propulsion is "too many connections" and other arguments of this ilk. I find the "many connections" of my Tesla battery modules to be genius engineering. I have 4 x 24V Tesla modules which each of 444 cells (18650s) in 6 series groups of 77 parallel cells. They are spot welded by robots at each end via a 10-15A wire which serves as a fuse if the cell misbehaves leaving the other 76 cells to take up the slack and reducing the whole pack capacity by a tiny amount. In 25 years (predicted lifetime of Tesla packs given current trajectories from older cars), these packs will look/operate almost exactly as they do now, albeit with diminished capacity (expected between 80-90% of new), all with no maintenance.

In contrast, there's a very long series chain of potential failures in a diesel which requires vigilance and routine, frequent maintenance. Rubber hoses, seals, filters injectors, strainers, elbows, mounts, heat exchangers needing re-coring/replacement, the list goes on. For me, and many considering electric propulsion, "We" choose not to "consider" further this complexity in favor of the simplicity of a well-engineered and largely maintenance free alternative.

As for battery capacities, just to throw in a bit of practical data from our 4 months of use thus far, admittedly a small dataset: our pack totals 21.2kWhr (4 x Tesla modules of 5.3kWhrs each). Our boat will move 2-3 knots with just 1.2-1.5kW (total) power from 2 POD drives (~600-750W each). It'll even still move around 1.5 knots with only 700W total. Half of our battery would thus provide 20 miles of range, but at that power level, one can imagine (and I hope to realize) a potentially dramatic contribution from solar. We've only got 610W now, but our cat can easily support 3 times that, and used panels are dirt cheap ($90/305W), so even with shading, we could potentially cruise at 3 knots as long as the sun is out, and this can happen day after day with no fuel to worry bout. It's perhaps not as fast as a diesel with hundreds of gallons available would manage the same task (getting out of the doldrums or sea of cortez), but it's a realistic and viable alternative right now, not some theoretical time in the distant future.

[MichaelPrichard]

Originally Posted by wingssail

seandepagnier, I'm sorry, and respectfully, I think you have some loose screws somewhere. You are actually suggesting a propeller which is 50% the size of the beam of your boat?

Bottom lines seandepagnier:

For going slow under power a big propeller is more efficient. For normal speeds, and for many other reasons, a smaller propeller is better.

For regen, even the most efficient repeller is simply a drag device which slows the boat MORE than the amount of power it produces.

HP is HP. No electric engine is going to propel a boat, using the same propeller, any faster than a diesel (or gasoline, or any fuel source, of the same horse power. The propeller does not know how the shaft is being turned. To think otherwise is ignoring physics.

And MOST OF ALL, regardless of how nice and quiet and clean and simple an electric purports to be, the fact that you cannot carry a fuel source to go 500 miles means they are a non-starter for the vast majority of cruising vessels. When they can, come back to us.

I think we're a long way from agreeing on what the "Bottom Line" is, so I'm trying to refrain from applying personal preferences and non-experimentally proven assertions of value. I am personally very interested in the salient details of prop diameter and efficiency, and I'm especially curious as to why the industry has "optimized" toward the solutions which abound, so I find exploration of the large diameter prop concept that Sean has been highlighting fascinating, especially if it can mean a doubling of my battery range.

When replacing our inboard diesels, I chose to avoid mounting the POD drives in the old sail drive locations (a common choice) since they offered me the option of retractability like Seawind catamarans and smaller monohulls have been doing for years. The props are thus never fouled with growth, are out of the water eliminating drag and saving on the costs of a folding prop, and thus allowing for some experimentation to find my preferred "optimization" rather than the industries. I've enclosed a few pics of my installation showing one possible method (at least in a catamaran) of doing retractibility with some wider flexibility of hull spacing allowing for larger diameter; clearly I'd need to restrict my setup to 2 blade props once I've exceeded the intersecting diameters when they're stowed.

As for "HP is HP", I'd beg to differ; a diesel engine will never produce an ounce of thrust from the sun, or from the sails, or from the wind. An electric motor can via all 3. It can also do so from electricity generated by a diesel. Apologies for my mis-characterization of your statement which I do understand (power is power), it's just a good example of the disconnect I'm seeing from folks exploring new alternatives to traditional diesel propulsion and those that attack often non-salient details at the expense of the larger picture; moving sailboats through the water via different means.

[wingssail]

Originally Posted by MichaelPrichard

...It's perhaps not as fast as a diesel with hundreds of gallons available would manage the same task (getting out of the doldrums or sea of cortez), but it's a realistic and viable alternative right now, not some theoretical time in the distant future.

Correction: to move our 43' liveaboard sloop with ourselves, provisions, spares, and all of our worldly possessions aboard, 500miles at 6.2kts requires only 60 gallons of diesel, not hundreds of gallons.

And, Mr Prichard, maybe you can move 2-3 knots with 1.2-15kw, which if I am not mistaken, is about two HP, but I'd say that in a seaway or against a headwind, you will need a bit more power, which will deplete your batteries a bit faster.

For example a situation common in our neighborhood is the rounding of Cabo Corrientes against wind and tide. We'd be sailing ourselves but most cruisers hereabouts will be motoring. It is not uncommon for them to come in telling us that they could only go 2 knots at full power, with their 45hp 4JH engines.

Check my math, but to do that with electric you'd need about 35kw of electric engine and about 105kWhr of batteries.

Basically electric power will remove that Cabo Corrientes rounding from your list of options. You just can't do it. Most likely you will respond by saying you don't want to anyhow. What else could you say?

Now, complexity: You have 1700 lithium batteries hooked up in a in 4 6S77P set up. You should a BMS (or several) which can open the bank relay (so you must have bank relays) in the event of a high or low voltage condition for that cell, you should have thermal cut-offs for each cell in case of a dangerous high temperature situation and a battery status monitor to sound alarms if the overall voltages get out of hand and to keep track of the state of charge. There should be protection against battery dumping by the BMS while engine charging to protect your alternator and some clever charge splitting to keep an engine starting battery charged when it has different charge profile. None of this addresses the shore power or solar power charging management.

None of ALL of that addresses monitoring and management of this whole system. (say a cell or a few drop off line, how do you know this happened? or a thermal cut-off trips?). Problem diagnosis becomes a job for a competent and maybe brave electrician. Is that you? If not, where do you g=find one in Papua New Guinea?

Instead, the DYI electric boat conversion guy just hooks it all up and assumes it will last 10 years without any failures anywhere among the 2000-4000 connections and electronic devices included in the system. It starts to make the diesel look sort of simple, and safe.

Electric is coming, but it is not here yet unless you overlook quite a few limitations and complications.

[newhaul]

Originally Posted by MichaelPrichard

This always confuses me; a common complaint about electric propulsion is "too many connections" and other arguments of this ilk. I.

That is not what I stated so don't put words into my mouth.
I am referring to the number of connections in your specific bank.

I am running lfp myself but alot fewer connections. My house bank consists of 4 250ah cells in a 1p4s for 12v nominal. All bolted. You are all electric spot welded and hard pounding vibrations will eventually cause them to fail . ( There is no flex) mechanical engineering 101.